Ultrahigh-frequency electron discharge device



1953 N. E. PRYSLAK ET AL ULTRAHIGH-FREQUENCY ELECTRON DISCHARGE DEVICE Original Filed March 28, 1947 Patented Aug. 4, 195 3 ULTRAHIGH-FREQUENCY ELECTRON DISCHARGE DEVICE Nicholas E. Pryslak, Florham Park, and Kenneth M. McLaughlin, Summit, N. J., assignors to Radio Corporation of America, a corporation of Delaware Original application March 28, 1947, Serial No.

737,890. Divided and this application September 30, 1948, Serial No. 52,082

5 Claims. 1

The present invention relates to electron discharge devices and more particularly to electron discharge devices useful at ultra-high frequencies, and to a method of manufacture and assembly of such devices.

This is a division of our co-pending application, Serial No. 737,890, filed March 28, 1947, now Patent No. 2,473,969, issued June 21, 1949, and assigned to the same assignee as the present application.

The invention relates generally to electron discharge devices of the type wherein the electrodes comprise concentric tubular elements and wherein one of the electrodes is supported on a conducting plate which extends through the Walls of the device envelope and is sealed thereto, and serves as an electrode lead. The invention particularly concerns an arrangement in such device wherein the grid is supported on the conducting plate.

The practice with respect to such electron discharge devices heretofore has been to provide the grid structure with an eyelet which is peened to a central aperture in the conducting plate for support thereon. The peening operation has involved the use of two tools, one to apply pressure to the eyelet from one direction to suitably deform it in peening and the other applied from the opposite direction to serve as a backing to absorb the pressure applied to the first tool. The use of tWo such tools has made accessibility to the grid and its supporting conducting plate or disc necessary simultaneously from the two opposite ends of the envelope of the device. In a structure involving this practice, the anode is supported at one end of the envelope and the cathode at the other end, the grid being mounted on the disc lead intermediate the anode and cathode.

Under the practice as heretofore followed requiring the use of two tools for peening the grid to its support, neither the cathode nor the anode can be mounted prior to fixing the grid to its support. This has resulted in the necessity for a two-part structure for forming each of the anode and cathode, one part comprising a portion of the tube envelope which is properly spaced and aligned during assembly of the envelope parts and serving as an electrode support and the other part comprising the electrode. These support parts are provided with longitudinal passageways therethrough which have sufiiciently large cross sections to accommodate the tools employed in peening the grid to its disc support'and for receiving the electrodes.

The use of a two-part structure for the electrodes which are mounted in the two extremities of the tube is characterized by many disadvantages. For example, a two-part structure has heretofore involved a discontinuity in the outer surfaces of the electrodes under consideration. Since ultra-high frequency devices of the type referred to are designed to function in association with concentric line conductors, the ridges or depressions in the outer surface of the electrodes referred to frequently interfere with proper engagement between such surfaces and contact fingers on the concentric line. Another respect in which a two-part electrode is undesir-,

able is the fact that such an electrode includes a substantial area between the two parts thereof which are not joined integrally but are merely in surface contact, which in some instances is incomplete. This defective surface contact affects ultra-high frequency operation in a harmful manner. For instance it contributes to a reduction in the radio frequency power output of the tube. Furthermore, a relatively close tolerance is required between the several parts of each of the electrodes referred to, especially the anode, to reduce as much as possible the loss in radio frequency power output. Such relatively close tolerance is difiicult to achieve and represents an added cost in the manufacture of the device.

While the practice in the manufacture of an electron discharge device of the type referred to of peening the grid to its disc support has made necessary a two-part structure for each of the anode and cathode electrodes in association with their supports, this manner of mounting the grid on its support is also accompanied by serious objections. Thus the peened'engagement between the grid and its support involves a surface contact which sometimes is defective and thus contributes to poor operation of the device at ultra-high frequencies, as explained above. In addition the force required in performing the peening operation sometimes results in damage to the device thus further adding to the expense of manufacture.

It is evident from the foregoing that the practice of peening the grid of a type of device under consideration, to its support, limits the anode and cathode to structures having the undesirable features mentioned and therefore modification to avoid the peening step in the method of mounting the grid on its support is necesasry before the problems presented by the structures of the other electrodes of the tube can be suitably dealt with;

But heretofore greater difiiculties have been encountered in alternative proposals for mounting the grid on its support than have been associated with the peening method. For example, a recourse to welding the grid eyelet to the apertured gridsiipport is accompanied by the danger that excessive heat might impair the glass-tometal seals of the device. The electric power required for welding would involve current conduction through the conducting plate or disc leadon which the grid is to be mounted. If this plate should be excessively heated there is the hazard that its seals to the glass envelope might be harmfully afiected. And due to the relatively large surface engagement between the eyelet of the grid and the disc lead a relatively large current value would be required for effecting a welded joint between these elements, and excessive heat in the disc, due to such large current value, would be difficult, if not impossible, to prevent. Accordingly it is an object of the invention to provide an improved electron tube useful at ultrahigh frequencies.

Another object is to provide an improved electron discharge device of the type employing concentric elements wherein one electrode is suppoitedon a'm'etal'plate sealed through the walls time envelope and in which the mounting of said electrode is accomplished in a novel manner. A further'object is to provide a novel method ofina'king' an electron discharge device in which structural limitations of at least certain of the electrodes are reduced.

"'An'additional object is to provide a method of making an electron discharge device of the type described in whichjaccess to the interior of the device duringmanufacture is necessary only from one end thereof.

A further object is to provide an electron discharge'device wherein no deflective surface contactexists between the respective input and output electrodes thereof and their supports.

An additional object is to provide an electron discharge device which can be employed advantageously in association with a concentric line.

Another object isto provide an electron discharge device in which the elements thereof have reduced tolerance requirements.

Astill further object is to provide an electron discharge device having improved radio frequency output at ultra-high frequencies.

nnadditi'onal object relates to a novel mounting'iof the grid on its support which avoids dere ctive surface "co'ntact' therebetween and eliminates the dependence on a two-part structure at mast-for one of the otherelectrodes for its accomplishment.

' Further objects and advantages of the invention will becomecl'ear as the description continues.

"While-the invention is pointed outwith particularityfin the appended claims, it may best be understood iromthe detailed description of an embodimentthereof taken in connection with the accompanying drawing, in which:

*Figure lshows a longitudinal section of an electron tube which includes the structure of our invention and has been made by our novel method; and

'Figures'2 to '5' inclusive illustrate steps in our novelmethod of manufacturing an electron tube, Figures 2 and 3 showing the step of positioning the grid on a welding electrode with its lower portion flared by being forced down on a shoulder'o'f thewelding electrodeyFigure 4 indicatifigin detail the engagement of the flared portion of the grid with beveled walls of the grid support, and Figure 5 depicting the relative position of the parts during the welding of the grid to its support.

Referring to the drawing in more detail there is shown in Figure 1 thereof an electron discharge device which employs our invention and which has been manufactured in accordance with our novel method.

Our-novel electron discharge device includes an envelope formed by tubular glass members 10, ll and the elongated metallic bodies I2, i3, the latter bodies serving as end closures of the device. Tubular electrodes comprising anode l4, grid l5 and cathode I 6, are mounted in concentric relation within the envelope.

Each of these electrodes and their supports and lead-ins are of novel construction contributing to easeof manufacture of the device and to good operation thereof. The advantages resulting from the novel structures 0nd Organizations of our invention will become apparent from the following detailed description thereof.

The anode M is part of the integral elongated flanged body I2, the several portions of which have different utility. The peripheral flange H on body 12 is sealed to glass member ['0 at I8. The fiange ll is positioned intermediate the ends of body l2 and closer to one end thereof than to the other. The shorter end portion it of body l2 extends into the envelope of the device and includes the work surface of the anode. Memher [2 has a passageway!!! extending longitudinally therethrough which includes the required recess in anode 14 for receiving the grid and cathodaand in addition affording communication between the exterior and interior of the envelo'pefor the purpose of evacuation. Since no tool is required to be inserted through passageway l9, it need not be wide. The exhaust tube 20 employed in such evacuation is shown pinched off to seal the passageway after completion of the device. The portion'of body 12 extending outside of the-envelopeserves as a lead-in for the anode.

The utilization of an integral body having portions-thereof serving in the several respects mentioned is accompanied by many important advantages. The device described is-intended to operate at ultra-high frequencies. At these high frequencies it is desirable to use'concentric transmission linesin association with the device. .Such transmission lines are usually connected to leadins of the device by means of fingers contacting the surface of such lead-ins. It is an aid in accomplishing the desired contact between these fingers and the'lead-ins if the surface of such lead-ins is smooth. If discontinunities should be presentin the lead-in surface, such as depressions or ridges, over which thecontact fingers of the line are required to pass, there is danger of improper contact between lead-ins. and the transmission line. 'If such contact is impaired, even -to a slight degree between the anode leadin and its associated transmission line, the output from the device will be inefficiently transmitted. The one-piecestructure of the anode and its lead-in as provided for by our invention, avoids discontinuities in the surface of the lead-in.

In organizations where the anodeand its leadin areseparatestructures, such breaks in the surface are difficult to eliminate. This is for the reason that structures of the general ,type under consideration have heretofore included a brazed joint between the anode and its lead-in at' a surface portion over which the contact fingers of the transmission line are required to pass.

Another respect in which the one-piece structure of the anode and its lead-in is advantageous is that it reduces losses in radio frequency power output. In the two-piece anode construction as heretofore employed, one piece comprised an outer sleeve for receiving the anode. Both parts were silver plated to provide a low resistance path to radio frequency and to facilitate sealing to lass portion of the envelope. It was necessary to ream this outer sleeve to extremely fine tolerances to receive the anode barrel in a snug fit. In some instances bare steel was exposed as a result of the reaming operation, which caused a noticeable loss in radio frequency power output. The inclusion of the anode in a one-piece structure, as our invention provides, avoids this power loss and eliminates the expense of the close tolerance reaming operation.

Employment of this novel and desirable onepiece structure of the anode is possible as a consequence of a further novel feature of our invention. This feature concerns structural characteristics of the grid [5 and its support 2|, which permit mounting the grid on its support by an operation that requires accessibility to the interior of the envelope from one end thereof only. These structural characteristics are, a grid of cage or wire construction throughout its entirety having one end 25- thereof spread or flared outwardly, and a grid support 2! of a plate-like structure having an aperture or passageway 24 therethrough provided with beveled or frustoconical walls.

These structural characteristics of the grid and its support permit a method of mounting the grid on its support to be used, which mechanically requires only a forced contact between the flared portion of the grid and the beveled walls of the passageway in its support. Such forced contact between these elements can be accomplished by applying a force longitudinally of the device through one end thereof to the flared end of the grid to seat this end in contact with the beveled walls in the support. Good contact between these parts results from the application of such longitudinal force because of the translation of a part of such force by the beveled and flared parts referred to, into a transverse component. The sum of such longitudinal and transverse components results in a force normal to the surfaces of the beveled walls of the passageway and the flared portion of the rid. To properly allow the grid end portion 25 to contact the beveled walls of the passageway 2d, the plate 2| is mounted with the wider end of passageway 24 therein, facing the open end of the device remote from the elongated member l2.

The forced contact between the flared end 25 of the grid and the beveled walls of passageway 24 is all that is required mechanically to fix the grid to its support but such surface contact alone is insufficient to complete the mounting of the grid on its support and a further non-mechanical means is employed to complete the mounting of the grid.

Heretofore one method of accomplishin a complete mounting of the grid on its support has involved the provision of an eyelet at one end of the grid and a peening of this eyelet to its support through a passageway therein having walls normal to a surface of the support. This has required the use of two tools applied from opposite end openings in the envelope. But the contact report.

sulting from such peening operation between the grid eyelet and the grid support was a pressure type friction contact and was objectionable in that it contributed to a loss in power output of the device.

Our invention eliminates the need for an eyelet on the grid and does not rely entirely on mechanical contact between the grid and its sup-- It is feasible according to our invention to provide a weld between the flared end of thegrid and its support. The relatively small surface engagement between the wire strands in the flared portion of the grid and the walls of the passageway in its support, requires a welding current of less magnitude than would be required. for welding a grid eyelet to the grid support.

The value of the current employed in the weldin of the grid to its support is important in connection with the device of the type described. It will be noted that the grid support 2| is sealed to glass members W, H at 22, 23. In welding the grid to its support, electric current would be required to transverse the supporting plate 2| including the portionthercof at which these seals are located. Too high a value of such current would heat the plate 2| to such an extent as to impair the seals referred to. Such undesirable high value of current would be required in welding a grid eyelet to the grid support due to the relatively large surface engagement involved therebetween, but is avoided according toour invention by the limited surface contact of the parts to be welded as explained above.

The welded joint between the grid and its support thus permitted by the novel structures of the grid and its support is advantageous from theseveral standpoints of providing a direct metal to metal contact between these elements, resulting in higher power output of the device, permitting a method of manufacture to be followed that requires only one open end of the device, and. allowing the use of a one-piece structure for the anode and its lead as described above.

The cathode end of the device, while subject to the requirement of providing a working space therethrough for accommodating tools required for mounting the grid upon its support, includes a novel structure that not only provides this necessary communicating space, but in addition contributes to ease of manufacture of the device and good operation thereof. The end of the device which includes the cathode I6 is provided with sleeve I3 having a peripheral flange 26 at one end thereof which is sealed to the envelope glass member ll at 21. Sleeve It also has an inwardly extending flange 28 which serves as an. abutment for sleeve 29 disposed within sleeve I3. Sleeve 29 is provided with a shoulder 30, the: surface of which is involved in the abutment re-- ferred to. Sleeve 29 is sealed to the inner wall of sleeve 13 at 3|, as by brazing. It will be noted that the sealing point is entirely within sleeve I3 and somewhat removed from the end thereof remote from the envelope. The end of the sleeve 13 remote from the envelope is suitably sealed as by a vitreous body 32. This manner of mounting the sleeve 29 within sleeve [3 does not require a vacuum type seal at 3|, since the vacuum type seal at this end of the device is made by body Cathode support sleeve 33 is mounted on the end of sleeve 29 which extends into the envelope of the device. Cathode I6 is in turn mounted on support 33. The cathode I6 is indirectly heated by means of a heater wire 34.

The advantages resulting from this structure It will be noted from the foregoing that the structure of the-endportions of the' device and the grid and its s'upport observe relationships whereby the features of one structure-are -'dependent on the'fe'ature's of orie or both" of the other structures. 1 Thus the one-piece structure of the anode end of the device is' dependent upon the structure of the grid and its supportwhich permits mounting' of thgrid from one 1 end only of the device; This manner of mounting'th'e grid is in turn dependent upon an adequate communicating space to the interior ofthe envelope through -the-oathodeend of the'devicew The structure-"of the-parts of' th'e device forming the" electrodes 'a'nd='-their lead ins 'or s'upports permits 'a -novel and advantageous r'ne'thod to be employed in their assemb1y to form the completed device} The envelope parts including the one-piece anode part i2, the-glass members I0, 'I l; the conducting plate 2] and the sleeve l3"arenfirst "assembled and sealed' to'gether' by the use of a ceirteringand-spacing mandrel or jig, not 'shownfl' lhi's results ina proper spacing and centering of a'node' i 4, conducting plate 2i and sleeve 3. -Th'e glass members H], i'l a'remroperly centered 'by ngagirigannular ridges on t e f g gfif'gj 9;; '-,1..:e'.-.' =1 Afterthese parts have been assempled and sealed 'as" ind-ic'ated 'the grid :1 5 is f'fixed-" to plate 21. Before-"applying th'egrid to the plate -='2l the grid is threaded on a portion 36 of-a 'we1ding rtool 3i having 1 a F shoulder sagas i'shown in Figure-2; Gr-idwtt irs-manually forced against shoulder 3B-unti1 one end thereof: engages the wider part-of shoulder 38. This step --results in the io'rmati'on f ir-flare 25at this" end of the grid as 'shown'in Figure 3 With grid (5 thus engaging the portiiin stand sho'u1de'1 38 or weldin'g tool 37', this tool is insertedint'othe'" pa'ssagew'ay"2 l in plate?! withitsshoulder 38 forcing the fiared"'erid -25 of grid I5- against*th'e beveled walls of the passageway. 1 Suitable longitudina'l pressu e- 1s'a iieci'io tool =3'i to assnre ee'nthe flared end "of the g'r'id good contact-be v i ails "referred to, F as shown gin and the lievele- Th ewelding tool 31 comprises one terminal of an electrical circuit which includes the flared end 25' of gri isjitjhe {conducting plate 2 if and amp shaped electrode 39 'as 'showndnFigure 5. Due'to jther elatively small area of surface engagement hetw ri'the wires ofi t he grid at'its fiared'jport'ioii' and t e" wallsof p ssageway '34, a weldin'ghurrent ef a 'value'ibelow that which would heatpl ate'fi ljto I an extent to imp'air' seals 22,113, is merit for 'accom'plish'ing' a weld between the n end ojf t e grid and the' 'w alls of the passageway;

Af tertheweld has been accomplished the welding'tool,31.is"re drrbmj e device and a cenwrin .'tqq i QW -i ii s liq l. iii t g sealed as by pinching.

the grid IS with respect to the anode it. This e'enter'ing tool engdgsth inner walls of sleeve [3, which have previously been 'eentered"with respect to' the anode. 1".

The centering tool is then withdrawn and the cathode structure comprising sleeve 2 9, supp'drt 33', cathode [[6 and heater 34,'is insertdin'isleve It. {This structure is "eentered with respeotfto sleeve 29- as bya jig; not shown. SleevefZBferfi gages the inner walls of sleeve 13 in. a re lativ'e ly-tight fit and the cathode is centered by" such fit with reference to the-grid l5' and anode it. The cathode structure is'so dimensionedthat when shoulder 39 on sleeve 29, engagesthe fia'nge 28 on sleeve I3; the c'a'tho'dlfi extends to "a de sired operating position-"within the" anodei' M and grid 15. With shoulder 3 EJ in abutment-with fiange 28 the end of sleeve 25 remotefrom the cathode'is'brazedat 3i'to sleeve*l3.;-' "Ifhere'after a stem of insulating material=32 such as glass is sealed across the open end o f sleevefll 3"w 'th the heater leads 34 passing"therethroughz 'ljhe final step in the manufacture of the deviceis the evacuation 'of the interior of the env'elope throughexhaust tube 20,'which'-is then 'The foregoing description of an embodiment of the invention is presented'with a viewtofiappris ing persons skilled in the art of one Way in which itmay-be carried out. 'Of necessity much detail not required for practicing the invention-hasheen included in this description: Itis'not intended, therefore; to limit the invention to the precise structures and organizations 's hown" andflescribed, but to permit it a'scop'e indicatedfby the appended claims. iij

' What we claim is:

1. Method of mounting a tubular and relative- 1y fragile grid on a disc' shapedsupport havinga passageway defined f'by walls of irhsto conical shape, whereby'one end of saidpassagewali'radjacent one flat side of said support is' wider' th'an the. other end thereof, said method comprising mounting said supportltransversely and-intermediate the ends ofanelongatedelectrorrtube envelope having an open end withsaiddne flat side of the support facing said open end and with said passageway in the suppdrt'incoagial rem-- tion with said envelope and said openendjflai-ring aperipheral' portion of said grid to said 'frusto-conical shape, extending said grid through said open end and through said passageway-wlth the wider'end' of said -frusto'-conical peripheral portion thereof in trailing' 'relationtothe "narrower-end of-said portion, untihsaid peripher'al portion seats onthe'walls of-saidpass'ageway in arelatively large area engagement, and passing electric welding currentthrough sa-id supportand said-peripheral portion of the'- grid to -weld s'aid grid to said support.

; 2 Method of mounting a tubular and relatively said passageway adjacent one" flat sidebf said support; said'method comprising the step'Soi first mounting said support within andappreciably s'pace'd fromthe ends ofan el'on'gated'electro'n' tubeenvelope having an open-"end; and

with aid relatively wide mouth facing said open end and coaxial therewith, deforming "a peripheralportion of said grid tosaid-zfrusto conical shape, engaging the inner surface ofsa'id."p'e

ripheralportion and extending said gridthrou'gh said open end and said passageway while so engaged until the outer surface of said peripheral portion engages said walls of said support in a forced contact, whereby the grid is free from additional deformation during the extending step and a relatively large area engagement is effected between said grid and said support, and welding said grid to said support at said relatively large area engagement for providing an improved weld.

3. Method of mounting a tubular and relatively fragile grid in a partly completed elongated electron tube having an open end and a disc-shaped support extending acros said tube intermediate the ends of the tube and having a passageway coaxial with said open end and defined by walls 1 diverging about 45 from the face of the support remote from said open end, whereby said passageway has a relatively narrow end for snugly receiving said grid, said method comprising deforming an end portion of said grid to provide a structure having walls diverging about 45 towards the free end of said end portion, extending said grid into said open end and through said passageway with the other end of said grid leading while engaging said grid at said end portion thereof, whereby said diverging walls of said end portion of the grid engage the diverging walls of said passageway in a forced contact of relatively large area for a good weld and with reduced hazard of further and undesirable deformation of said grid, and welding said diverging walls of said support and said grid for fixing said grid to the support.

4. Method of mounting a tubular grid on a relatively thin disc-shaped support having a passageway extending therethrough defined by walls of frusto-conical shape, whereby said passageway has a wider end adjacent one face of Said disc than adjacent the other face thereof and said walls have a relatively large area, said method comprising the steps of: simultaneously extending said grid through said passageway, with the leading end of said grid first entering the wider end of said passageway and deforming a portion of said grid adjacent the trailing end only of said grid to cause said portion to engage said relatively large area walls of said passageway in a relatively large area forced contact; and welding said grid portion and said passageway Walls to fix said grid to said support.

5. Method of mounting a tubular grid to ex tend through and be fixed to a relatively thin disc-shaped support in a relatively large area engagement, comprising puncturing said disc to provide a passageway extending therethrough for snugly receiving said grid and having walls flaring outwardly towards one face of said support at an angle less than 90 from the axis of said support, flaring an end portion including one end of said grid to said angle from the axis of said grid, extending the other end of said grid through said passageway from said one face of the support until the flared end portion of the grid seats on said walls of said passageway in a large area engagement, and welding said end portion and said walls to fix said grid to said support.

NICHOLAS E. PRYSLAK. KENNETH M. MCLAUGHLIN.

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